uency of f2 = 75 Hz. Take the speed of sound in air to be v = 340 m/s. Find an equation for the speed of the sound source, in this case the train

**Answer 1**

You have two unknowns here. The frequency of the whistle at zero velocity, and the speed of the train.

As it is approaching you then f2 = f1* 340/(340 – v1)